TB-500
Synthetic fragment of thymosin β4
A short, N-terminally acetylated heptapeptide corresponding to the actin-binding region of thymosin β4. In cell biology, a tool for studying cell migration and the cytoskeleton.
Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln
At a glance
- 01
The active core of a protein
Thymosin β4 has 43 amino acids. The LKKTETQ motif is the segment it uses to bind actin. TB-500 isolates exactly this region and allows the role of actin binding to be studied separately from the rest of the protein.
- 02
Cell migration as a research topic
Actin is the engine of cell movement. Peptides that interfere with actin dynamics are tools for questions of wound healing, angiogenesis and cell migration in vitro.
- 03
Small, water-soluble, stable
With seven amino acids and an acetyl group at the N-terminus, TB-500 is readily soluble and comparatively robust. A practical property for cell culture experiments.
Fields of research
- Actin dynamics and cytoskeleton
- Cell migration in vitro
- Angiogenesis
- Wound healing models
What it is
Thymosin β4 is a small protein found in almost all body cells, whose main job is to bind monomeric actin. It keeps the cell’s actin supply in reserve and thereby regulates when and where the cell builds filaments. TB-500 is the synthetic short form: the seven amino acids responsible for this actin binding, with an acetyl group at the start, as present in the natural protein.
What makes it special
TB-500 is an example of how peptide research works: take a protein, identify the active motif and test whether the fragment alone carries the effect. For thymosin β4 the LKKTETQ motif is well characterised. Whether and to what extent the isolated fragment reproduces the properties of the whole protein is an open research question, and that is exactly what makes it interesting.
What the studies say
The scoping review by McGuire et al. (2026) evaluated 80 studies on thymosin β4 and TB-500. The result is sobering and clear: the majority of papers study full-length thymosin β4, not TB-500. The evidence was gathered predominantly in vitro and in animal models, with a focus on wound healing and vascular biology. For the frequently discussed applications to tendons and ligaments, human data are almost entirely absent.
State of evidence
Preclinical: moderate, but mostly for the whole protein. Clinical: none. Anyone working with TB-500 should be aware that findings on thymosin β4 do not automatically apply to the fragment.
Research status
TB-500 is not approved as a medicine and is on the WADA prohibited list (S2). PURA LABS supplies TB-500 for research use only, not for human or animal use.